№ 1092 1) =
a + 2 2a 2 − a − 3 2a − 3 a + 2 2(a + 1)(a − 3 2 ) a − 2 = = ⋅ : a − 2 a 2 + 5a + 6 a − 2 a − 2 (a + 2 )(a + 3) 2a − 3
a + 2 2(a + 1)(a − 3 2 ) a−2 a +1 ⋅ ⋅ = a − 2 (a + 2 )(a + 3) 2(a − 3 2 ) a + 3
1 8b 2 + 8b + 2 2b + 1 2b + 1 b(b − 4) 2b + 1 (b − 4 ) 2) 2 + : ⋅ = ⋅ ⋅ = b b b b 2b b 2 − 4b 2(2b + 1)2
№ 1093 1)
= − + +
a a2 − 1
+
a2 + a − 1 a3 − a 2 + a − 1
+
a2 − a − 1 a3 + a 2 + a + 1
−
2a 3
=
a4 − 1
a a2 + a − 1 a2 − a − 1 + 2 + 2 − (a − 1)(a + 1) a (a − 1) + (a − 1) a (a + 1) + (a + 1) 2a 3
(a − 1)(a + 1)(a 2 + 1) 2
a − a −1
(a + 1)(a
2
)
+1
a2 − a −1
(a + 1)(a
−
(
2a
3
(a − 1)(a + 1)(a 2 + 1)
=
2a 3
−
)
=
(a − 1)(a + 1)(a 2 + 1) a (a 2 + 1) + (a 2 + a − 1)(a + 1) + (a 2 − a − 1)(a − 1) − 2a 3 = (a − 1)(a + 1)(a 2 + 1) 2
)
a a2 + a − 1 + + (a − 1)(a + 1) (a − 1) a 2 + 1
=
+1
Преобразуем числитель полученной дроби а(а2+1)+(а2+а–1)(а+1)+(а2–а–1)(а–1)–2а3=а3+а+а3+а2+а2+а–а–1+а3 – – а2 – а2 + а – а + 1 – 2а3 = а3 + а, тогда дробь примет вид
a3 + a
(a − 1)(a + 1)(a 2)
=
2
1 2
a + 5a + 6
1
)
) (a −1)(a + 1)
+1
+
(
a a 2 +1
=
2
2a 2
a + 4a + 3
+
2a
2
+
=
a 2
a −1
1
(a + 1) +
2
+ a +1
1
−
2 = a+3
−
2
(a + 2)(a + 3) (a + 1)(a + 3) (a + 1)(a + 2 ) a + 3 1 ⋅ (a + 1) + 2a (a + 2 ) + 1 ⋅ (a + 3) − 2(a + 1)(a + 2 ) = = (a + 1)(a + 2 )(a + 3) = 146
=
a + 1 + 2 a 2 + 4 a + a + 3 − 2a 2 − 6 a − 4 0 = =0 (a + 1)(a + 2)(a + 3) (a + 1)(a + 2)(a + 3)